Hmmmm...you'll probably get a lot of ideas on this one, let me be the first to throw a few out there.
First, how did he sound and what could you read from him (body language etc) when he said "I was thinking of going out for some beers"?
Was it suggestive...as in wanting you to come along?
Or was it more like a preemptive strike...like "just so you know, I have plans to go out"
Why do I feel like it was the latter?
IF I'm right, I wouldn't pin too many hopes on him asking you out...
How do you think he'd take it if you just plain old asked him? Could you put it like..."Did you want me to go with you for a few drinks? Because that would be great, but if not I can make plans to go out with...."
Just a tough one to call, since he's been so DARNED confusing on the whole "YOU don't want to do things with me" craziness!